Terminal insulators



R. W. JOHNSON TERMINAL INSULATORS March 29, 1966 Filed Sept. 4, 1964' INVENTOR. 90:55 14 Joy/vso/v W Patented Mar. 29, 1966 3,243,504 TERMINAL INSULATORS Russell W. Johnson, 1047 Fairhrook Lane, Santa Ana, Calif. Filed Sept. 4, 1964, Ser. No. 394,520 3 Claims. (Cl. 174-138) The present invention relates generally to terminal insulators, and more particularly to insulators for use on relatively heavy duty transformers.

As is well realized, electrical transformers are a very vital and necessary element in affording electrical .power to the many factories, ofiices and homes. Not only are electrical transformers used along the transmission routes from the source of generation of the electrical power, but they are also used immediately outside the individual homes and other dwellings, and hence are vital links in inexpensively and effectively transmitting electrical power to the point of consumption.

The reason for such extensive use of transformers is manyfold, but principally'they are necessary due to the relatively high voltages at which electrical power is transmitted. To minimize losses in the electrical power while his being transmitted over vast distances, it is necessary to have the power at relatively high voltage and low current. However, electrical power in such condition is not particularly. useful for industrial or household purposes, so that such power must ultimately be reduced in voltage at the destination.

As a result of the foregoing, there are untold numbers ofelectrical transformers in use today. Most of these transformers were installed a number of years ago and have operated generally satisfactorily since that time.

However, it has been found that due to the unguarded or uncovered condition of the terminals on such transformers, certain complications arise. For instance, the exposed terminals present a hazard to human beings such as-electrical linemen who rnaintain-and replace such transformers, and also many birds and animals frequently come in contact therewith.

Not only is it dangerous for the small animal or bird which comes in contact with the hot terminal, but, of considerable importance to the electrical service company, since such transformers can be injured to a point where repair or replacement is necessary. This has been found particularly true where birds perch on the terminals and create a short or direct connection across the transformer itself. Not infrequently, two birds will perch on the opposite terminals of the transformer and touch each other. The result is that in addition to the birds being electrocuted, the transformer is burned out thereby necessitating repair or replacement.

' An object of the present invention is to provide a terminal insulator for use on electrical transformers and the like, which can be easily installed without requiring disconnection of lead Wires to the transformer.

Another object of the present invention is to provide a terminal insulator as characterized above which when installed firmly grips the terminal or terminal bushing so as to be rigidly held in assembled position.

Another object of the present invention is to provide a terminal insulator for transformers as characterized above which can be conveniently gripped by a lineman with his hot stick to enable him to install the insulator without disconnecting lead wires or the like.

A still further object of the present invention is to provide a terminal insulator or guard as characterized above which substantially completely encloses the terminal or terminal bushing on which it is installed to clearly prevent inadvertent electrocution of human beings, animals and birds. I

Another further object of the present invention is to provide a terminal insulator as characterized above which is simple and inexpensive to manufacture, and which is rugged and dependable in operation.

The novel features which I consider characteristic of my invention are set forth with particularity in the appended'claims. The device itself, however, both as to its organization and mode of operation, together with additional objects and advantages thereof, will best be understood from the following description of specific embodiments when read in connection with the accompanying drawings in which:

FIGURE 1 is a fragmentary elevational view of a transformer and mounting means therefor, having installed thereon insulators according to the present invention;

FIGURE 2 is a front elevational view of one of the terminal insulators or guards of FIGURE 1;

FIGURE 3 is a longitudinal sectional view of the insulator of FIGURE 2; and

FIGURE 4 is a transverse sectional view thereof.

Like reference characters indicate corresponding parts throughout the several views of they drawings.

Referring to FIGURE 1 of the drawings, there is shown therein a transformer 10 positioned on a platform 12 which is cantilevered from a mounting pole 14. The transformer shown in FIGURE 1 is merely for purposes of illustration, and may take. substantially any form in accordance with good transformer design. Transformer 10 comprises a cap or cover 16 from which extend a pair of terminals 18.

Each terminal 18 is provided with a predetermined amount of insulator material 20 which is usually formed of ceramic materials of sufiicient thickness and dielectric strength to afford the proper insulation qualities.

To enable lead wires and the like to be connected to the transformer 10, each such terminal 18 further comprises aterminal end portion which extends beyond the insulation 20. Such end portions are usually made of brass, copper or other electrically conductive material, and are provided with fastening-means such as a terminal nut whereby the end of lead wires 22, as shown in FIGURE 1, can be connected to the transformer.

Inserted over the terminal bushing of terminals 18 of FIGURE 1, are insulators or guards 24 according to the present invention. As shown more clearly in FIGURE 2 of the drawings, each such insulator 24 is formed with a generally cup-shaped housing 26 which comprises a generally tubular body 28 having a closed end 28a and an open end 28b. The body 23 is generally tubular in construction to provide a continuous side wall for the housing 26 which is generally circular in cross-section as shown most clearly in FIGURE 4 of the drawings.

An end wall 30 for tubular member 28- is provided at the end 28a to effectively and electrically close that end of the housing 26. As will be apparent to those persons skilled in the art, the tubular body 28 and end wall 30 may be formed integrally, if desired, of any one of various plastic materials presently available. Such material, however, must be a good electrical insulator and must be impervious to all weather conditions so that the terminal bushing is protected at all times.

Mounted on the dome-shaped end wall 30 of housing 26 is a generally cylindrical extension 32 which may be formed integrally with the end wall if desired. Such extension 32 should be of such shape and size as to be conveniently gripped by a lineman with his hot stick. The latter is a tool frequently used by electrical lineman when working around live or hot electrical devices to avoid contacting energized elements.

The body 28 of insulator 26 is formed with a slot or elongated opening 34 which extends longitudinally of 3 the body 28 from the marginal edge of the open end 2% the e T .fae itat ineertiea of he insulator en terminal bushing as will hereinafter appear, the entrance 34a to slot 34 may be enlarged and/or beveled such as by providing thebody 28 with arcuate edges 280 as shown in FIGURE 2.

At the closed end 23;: of body 218, there is provided a transverse slot 36 which cooperates with the longitudinal slot 34 to provide a generally T-shaped opening. The transverse slot 36 affords some degree'of flexibility to the body 28 on either side of slot 34 to facilitate insertion of the insulator 24; on a terminal bushing as will hereinafter appear.

Adjacent the juncture of slots 34 and 36, there is pro- Yided n a iw l Op nin of r e 38 fo rec ng nd retaining lead wires as Will hereinafter appear. Such recess 38 cooperates with the junction of slots 34 and 36 t P v e ail la ed Queu or r ceivi g the l ad wires.

As shown most clearly in FIGURES 3 and 4 of the drawings, positioned Within housing 26 is generally cupshaped insulation 40. Such insulation does not extend to the marginal edge of end 28b of body 26, but rather is spaced therefrom as shown in FIGURE 3 to cause the open end of housing 26 to act as a protective skirt as will hereinafter become readily apparent.

Insulation 40 is provided with a longitudinal slot 42 which is similar to the slot 34 in housing 26; and

A which is aligned therewith as shown in FIGURES 2 and 3. It should be particularly noted that insulation 40 has a relatively deep or thiclg side wall as shown at 40;: and is formed of resilient fire retardant plastic foam. As such, the side wall acts as a cushion in that it is relatively deep and extraordinarily resilient. Such plastic foam insulation, it will be noted, also extends along the inside of the end wall 30 of housing 26.

To install the subject terminal insulator, it is merely necessary for the lineman to grip the extension 32 of housing 2 6'with his hot stick. Thereafter, the entire insulator can be placed over the terminal or terminal bushing without disconnecting any lead wires connected thereto. The central opening of the insulation 40 should be smaller than the external dimensions of the bushing to be engaged. As such, the insulator is forced downwardly over the terminal bushing, the resilient insulation 40 serving to firmly grip the terminal bushing to retain the insulator in assembled position.

The insulator .4 is inserted over the terminal bushing with the slots 34 and 42 aligned with the lead wires 22. The relatively wide and tapered entrance 34a to the slot 34 allows a certain margin of error in the linemans initial placement of the subject insulator over the terminal bushing With the lead wire 22 at the entrance 34a to slot 34, the entire insulator is firmly pushed onto the terminal bushing. The lead wires thus pass along the slots 34 and 42 until they reach the recess 38. The insulator 24 is thus properly installed with a minimum of eiiort and time.

9 By having the insulation 40 of proper length for the terminal bushing, it is seen that the lower end 2812 of body 28 acts as'a skirt or shroud for encompassing the adjacent portion of the insulator 20. Thus the entire bushing and other energized parts of the terminal are eompletely' enclosed.

4. It is thus seen that the present invention provides a terminal or erminal bushing insulator which can be easily and firmly installed without the need for disconnecting lead wires thereto or any other components associated with the transformer. Also, such insulator can be quickly and effectively removed merely by gripping the extension 32 and forceably pulling the insulator from theterminal or terminal bushing.

When installed, the subject insulator completely isolates the various parts which are electrically energized to prevent inadvertent or accidental electrocution of humans, animals or birds.

I claim:

1. A terminal insulator for transformers comprising in combination, a generally cup-shaped housing having a generally tubular body of circular cross section, said hnusing also comprising a generally dome-shaped end wall at one end of .said tubular body to provide a closed end for said body, said body being formed with a longitudinal slot extending from the marginal edge of the open end of said housing to the closed end thereof adjacent said end wall, said body also being formed witha transverse slot intersecting said longitudinal slot to provide a pair of generally flexible Wall portions on opposite sides of said longitudinal slot, said body further being formed with a relatively large opening at the intersection of said longitudinal and transverse slots to. loosely receive an electrical conductor, tubular insulation within said hous-v ing formed with an elongated slot aligned with said longitudinal slot in said housing, and a cylindrically shaped extensionon said housing to be gripped with an insulated tool whereby said insulator can be firmly anchored on a bushing withou-t creating additional force, on an electrical onduct connected ther to, pre sure on said insulator While said longitudinal slot is aligned with the electrical conductor to said terminal bushing causing,

a generally flexible al po io o a tubular bo y to open said longitudinal slot to permit said electrical conductor to be loosely positioned in said relative large opening at the intersection of said slots.

2. A terminal insulator tfor transformers according to claim 1, wherein the marginal edge of said tubular body is rounded at said longitudinal slot to facilitate opening of said longitudinal slot by pressure on said insulator, 3, A terminal insulator for transformers according to claim 2, wherein said tubular body and dome-shaped end Wall are formed of relatively tough and generally inflexible plastic material which becomes sufficiently flexible to permit said longitudinal slot to open only when formed with said predetermined wall portions as provided by said longitudinal and transverse slots.

References Cited by the Examiner UNITED STATES PATENTS 1,564,321 12/1925 Cameron 174-5' 1,931,949 10/1933 Lockyer 339-116 2,205,039 6/1940 Johns 174-5 2,717,588 9/1955 Arvanitakis 174.l39. X 2,740,001 3/ 1956 Vergili-o et al. 17413'8 2,922,836 1/1960' Brown 174-153 3,019,287 1/1962 Newcornb et al. 174-5 X LARAMIE E. ASKIN, Primary Examiner. 

1. A TERMINAL INSULATOR FOR TRANSFORMERS COMPRISING IN COMBINATION, A GENERALLY CUP-SHAPED HOUSING HAVING A GENERALLY TUBULAR BODY OF CIRCULAR CROSS SECTION, SAID HOUSING ALSO COMPRISING A GENERALLY DOME-SHAPED END WALL AT ONE END OF SAID TUBULAR BODY TO PROVIDE A CLOSED END FOR SAID BODY, SAID BODY BEING FORMED WITH A LONGITUDINAL SLOT EXTENDING FROM THE MARGINAL EDGE OF THE OPEN END OF SAID HOUSING TO THE CLOSED END THEREOF ADJACENT SAID END WALL, SAID BODY ALSO BEING FORMED WITH A TRANSVERSE SLOT INTERSECTING SAID LONGITUDINAL SLOT TO PROVIDE A PAIR OF GENERALLY FLEXIBLE WALL PORTIONS ON OPPOSITE SIDES OF SAID LONGITUDINAL SLOT, SAID BODY FURTHER BEING FORMED WITH A RELATIVELY LARGE OPENING AT THE INTERSECTION OF SAID LONGITUDINAL AND TRANSVERSE SLOTS TO LOOSELY RECEIVE AN ELECTRICAL CONDUCTOR, TUBULAR INSULATION WITHIN SAID HOUS- 